By AMANDA BARNIER
Can you recall what you were doing last Wednesday between 2.15pm and 2.36pm? Where were you? What did you see? Who did you talk to? How well do you remember those 21 minutes?
Now try to recall Wednesday six weeks ago. What about a Wednesday 15 years ago?
How detailed and accurate do you think your memories are of these recent or long-ago events?
An addictive new weekly podcast, Serial, asks questions such as these to “search for the truth” about the murder of 18-year-old American student Hae Min Lee.
On Wednesday, January 13 1999, Hae disappeared in Baltimore County, Maryland. Four weeks later her body was found in a shallow grave in nearby parkland; she had been strangled. Six weeks later Baltimore City detectives arrested Hae’s ex-boyfriend, Adnan Syed.
Adnan’s trial hinged on where he was for 21 minutes between 2.15pm and 2.36pm on the day Hae disappeared; the time she died.
The state’s case against Adnan and his eventual conviction for first-degree murder relied on the testimony — the reported memories — of another teenage boy named Jay. There was little or no physical evidence linking Adnan to the crime. Jay said Adnan murdered Hae. Adnan said he had nothing to do with it and didn’t know who did.
Adnan Syed in 1998. Image courtesy of Serial.
Serial’s host and co-producer, Sarah Koenig, tries to piece together what happened through memories: memory reports from then, as told at the trial; and memory reports from now, 15 years after these events, of Adnan (who is serving a life sentence in jail), Jay, their classmates, friends, families, the police and even Hae (via the diary she left behind).
Koenig’s search, successful or not, raises fascinating questions about the nature, meaning and complexities of personal recollections.
1. How does memory work?
In essence, memory can be thought of as a sequence of information-processing stages with three basic tasks:
- get information in (encoding)
- save information over time (storage)
- get information out (retrieval).
As we go about our daily business, we perceive and experience things that are captured in great detail and go into sensory memory for a brief period of three to four seconds. Most of this information we lose. But information that we pay attention to or that captures our attention is transferred to short-term memory; this is what is in your mind right now (the words of this article, for instance, and their meaning).
Short-term memory can hold a small amount of information (seven items, plus or minus two) for a limited time (about 15 to 20 seconds). If we don’t use that information almost immediately (such as dial a phone number we’ve just been told) or rehearse it, we forget it. But if rehearsed, it becomes encoded and can be stored in long-term memory.
Information that reaches long-term memory can last there for long periods of time and be retrieved – brought to consciousness – as a memory report or behaviour, such as dialling that phone number again.
So for Adnan, Jay and their friends to remember what happened on the day Hae disappeared 15 years ago they need to have encoded, stored and be able to retrieve those memories.
But memory is never guaranteed. An event may not be encoded in the first place, it may be difficult to retrieve, or it may be lost from storage.